"Using a Mac may certainly be a safer choice for a lot of people as despite being vulnerable they are not targeted. However this is not the same as Macs being secure, something Eric Schmidt erroneously advised recently. I may be able to browse impervious to malware on a Mac at the moment, however I personally would not be comfortable using a platform so easily compromised if someone had the motivation to do so. In this article I address just why OS X is so insecure including the technical shortcomings of OS X as well as Apples policies as a company that contribute to the situation."

The problem is that it's not only pirated torrents. No closed-source software distribution channel can be deemed perfectly secure, because there's no way to check a binary for existence of backdoors. Which is why all software should be sandboxed.